Reviewed by USGSNew Caledonia22y ago
M5.5 earthquake 164 km ESE of Tadine, New Caledonia
Saturday, August 21, 2004, 11:33:40 UTC · 22.038°S, 169.377°E
A magnitude 5.5 earthquake struck 164 km ESE of Tadine, New Caledonia on Saturday, August 21, 2004, 11:33:40 UTC, at a depth of 10.0 km (shallow). It is the strongest earthquake within 300 km since an M5.8 on July 20, 2004.
- Magnitude
- 5.5
- Moderate · mwc
- Depth
- 10 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- —
- No ShakeMap
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeDashed circle: 75 km aftershock search area
In context
How big was it, and why here?
Energy released
3 kilotons of TNT
That is about 1/6 of the Hiroshima bomb. It released about 6 times the energy of a magnitude 5.0.
Tectonic setting
8 km
from the nearest mapped plate boundary, between the New Hebrides and Australian plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
10 km
Shallow earthquakes (under 70 km) produce the strongest surface shaking for their size, so they are the ones most likely to cause damage near the epicenter.
Did You Feel It?
Where it was felt
No “Did You Feel It?” reports have been published for this event yet. If you felt it, you can add your report on the USGS website.
I felt it — report to USGS ↗USGS PAGER estimate
Who was exposed to shaking
USGS publishes PAGER impact estimates for significant earthquakes, usually within an hour. No PAGER estimate is available for this event.
After the main event
Aftershocks within 75 km
USGS lists 4 M2.5+ earthquakes within 75 km in the following 30 days; the largest was M4.7 on September 4, 2004. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 892 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.11920 Vanuatu EarthquakeSeptember 20, 1920 · 247 km N of this epicenter
- 7.828 km ESE of Isangel, VanuatuJune 16, 1910 · 272 km N of this epicenter
- 7.7249 km E of Vao, New CaledoniaMay 16, 1995 · 120 km SE of this epicenter
- 7.6274 km ESE of Tadine, New CaledoniaMarch 16, 1928 · 111 km E of this epicenter
- 7.5southeast of the Loyalty IslandsJanuary 4, 1998 · 161 km E of this epicenter
- 7.3201 km ESE of Tadine, New CaledoniaDecember 27, 2003 · 40 km E of this epicenter
- 7.2southeast of the Loyalty IslandsNovember 14, 1906 · 237 km E of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 13 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 26 recorded deaths. The most severe:
- 1875M8.1
Loyalty Islands: Lifou Island
28 Mar 1875 · 244 km away
26 deathsSevere damage ($5–24M)tsunami
- 1901M7.9
Loyalty Islands
9 Aug 1901 · 64 km away
Moderate damage ($1–5M)tsunami
- 1920M8.1
Loyalty Islands
20 Sep 1920 · 247 km away
Limited damage (under $1M)tsunami
- 1913M8.1
Vanuatu Islands
14 Oct 1913 · 285 km away
- 1995M7.7
Noumea; Vanuatu: Port-Vila
16 May 1995 · 120 km away · intensity III
tsunami
- 1910M7.5
Vanuatu Islands
1 Jun 1910 · 230 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.